Re: World missing
@ChildzPlease I've moved your post to the Sims 3 PC tech section.
Are you logging into the Sims 3 Store with the same credentials (email address and password) that you use on Origin? Are these the same credentials you used to buy Monte Vista originally? If so, it's possible that the store isn't properly showing Monte Vista as owned, but you still may be able to download it either from your purchase history or directly from its product page.
https://store.thesims3.com/montevista.html?categoryId=12642§ion=UpSell
By the way, if you never registered your Monte Vista code directly in the store, it wouldn't show up on your account. You should have received a 16-character code when you bought MV. If you never used it, you should still be able to now: sign into the store, scroll to the bottom of the page, and click Redeem a Code.
If you can't find the code, or you did register it but still can't download MV, you'll need to contact EA customer support. Someone on that end can verify your purchase and manually add the world to your account.